1. Field of the Invention
This invention relates to a light beam scanning recording device which records a color image by two-dimensionally scanning a recording material with light beams of a plurality of different wavelengths modulated according to information to be recorded, and more particularly to a light beam scanning recording system in which recording is effected simultaneously along a plurality of main scanning lines.
2. Description of the Related Art
There have been known various light beam scanning recording devices in which a color image is recorded on a recording material by modulating light beams of a plurality of different wavelengths according to an image signal and scanning the recording material in a main scanning direction and a sub scanning direction with the modulated light beams.
In such light beam scanning recording devices, each recording light beam is modulated by directly modulating a semiconductor laser which is used as a light source or by use of an external light modulator such as an acoustooptic modulator or an optoelectronic modulator, and intensity modulation, pulse width modulation or pulse number modulation is generally employed.
In order to record a high quality image at a high speed using such light beam scanning recording devices, it is necessary to increase the amount of light projected onto each picture element and widen the dynamic range. Such a requirement can be met by using a light source of a high output power and setting long the recording time for one picture element so that the pulse width and/or the pulse number can be modulated over a wide range.
However, increase in output power of the recording light source is inherently limited and especially when a semiconductor laser is used, the output power of the laser cannot be satisfactory. Further attempts have been made to increase the amount of light projected onto each picture element by combining light beams emitted from a plurality of semiconductor lasers into a single beam. However this approach is disadvantageous in that there is required a combining optical system which must be highly accurate in alignment, which adds to cost of the device.
On the other hand, when the recording time for one picture element is set long, the recording speed lowers.